Industrial buildings have roof structures that typically include inclined rafter beams that extend parallel to each other and are sloped from the eaves up to the ridge of the building structure. Horizontally oriented purlins are mounted on the rafters and extend parallel to each other in a direction normal to the rafters. The purlins are supported by the rafters and flexible sheet material, such as blanket insulation, is spread over the purlins. The lengths of the blankets can extend either normal to or parallel to the purlins. Hard roof panels are applied on the insulation and are connected through the insulation to the purlins.
In recent years, flexible insulation blankets have been applied to industrial buildings by orienting the lengths of the blankets parallel to the purlins and placing the opposed side edges of the blankets on the tops of the purlins so that each blanket spans the space between adjacent purlins. This procedure of applying the flexible sheet material to the purlins during the construction of a roof has the advantage of mounting the edges of the sheets on top of the purlins so that there are no seams between adjacent sheets that are directly exposed to the space below the purlins of the roof. This helps reduce the penetration of heat, moisture and other items carried by the environment within the building through the seams between the sheets to the roof panels.
In order to apply the blanket insulation to the purlins of the roof structure, a reel support carriage such as those disclosed in U.S. Pat. Nos. 3,559,914, 3,969,863, 4,075,807, 4,147,003, and 4,967,535 can be mounted on the purlins of the roof for supporting one or more of the reels of blanket insulation. The reel support carriage, sometimes known as a “roll stand,” is guided by adjacent ones of the purlins and supports a supply of flexible sheet material, such as a reel of blanket insulation, above the space between the adjacent purlins.
Usually, a plurality of the reel support carriages are mounted on the purlins in two rows, with the first or forward row of carriages mounted over alternate spaces between the purlins and the second or rear row of carriages mounted over the other alternate spaces between the purlins. The workers stand on the hard roof panels that already have been applied to the purlins and push the carriages with push bars farther along the purlins to apply the blanket insulation as the blankets unroll themselves in response to the motion of the carriages. When the carriages have been pushed far enough away from the last applied roof panels, additional roof panels are applied to the purlins in the space between the last installed roof panels and the second row of carriages, and the procedure continues.
While the above noted process is suitable for applying blanket insulation to the purlins of a roof structure, other types of flexible sheet material can be applied in the same manner. For example, reflective sheet material, phase change material, and virtually any type of flexible sheet material that can be mounted on a carriage and progressively paid out from its supply and applied to the purlins can be installed in this manner.
One of the problems that is encountered in applying sheet material, such as fiberglass blanket insulation, to the purlins of industrial buildings is that the sheet material is suspended from its side edges that are applied to the tops of the purlins and the center portions of the sheets have no support and tend to sag between the purlins before the hard roof panels can be applied to the roof. Once the hard roof panels are applied by the insertion of fasteners through the hard roof panels down through the edges of the insulation sheets into the purlins, the sheet material becomes stabilized in its shape. If during the installation process the central portion of the sheet material is supported, the sagging of the central portion of the sheet material will be minimized after it has been installed. However, when the carriages that support the reel of sheet material are moved away from the previously installed hard roof panels, the insulation tends to sag downwardly between the purlins due to its lack of support before the roof panels are attached. This problem is affected by wind, the flexibility of the sheet material, the performance of the reel support carriages and the lack of experience and capability of the installers.
One of the solutions used in the industry to avoid the sagging of the sheet material between the purlins during the installation of a roof of an industrial building is to install metal bands in the roof structure before the sheet material is installed. The metal bands extend parallel to and between adjacent purlins at the desired height of the sheet material, thereby providing support for the sheet material when laid on the purlins and avoiding the sagging as described above. While the use of the support bands has reduced the problem of sagging insulation in the spaces between the purlins, the bands are expensive and are expensive to install at the building site. Moreover, the support bands have little function after the roof has been completely installed since the fasteners and hard roof panels adequately support the sheet material at the edges of the sheets and prevent excess sagging of the sheet material between the purlins. Further, the bands tend to compact the insulation more than when the insulation is suspended between the purlins without the use of bands. Compacting the insulation results in reduced insulating capacity of the blankets.
I developed an insulation carriage that includes a sheet support that extends from the carriage back beneath the previously paid out segment of sheet material toward the last applied hard roof panels, as disclosed in U.S. Pat. No. 4,967,535. The sheet supports of the carriages of the '535 patent support the sheet material extending from the second row of carriages that are close to the previously applied to the roof panels, but do not adequately support the sheet material when the carriages are moved away from the roof panels, particularly the first row of carriages that are always farther away from the roof panels. Also, the sheet supports of the '535 patent must be installed on all of the carriages and the carriages must carry the weight of the sheet supports, making the carriages heavier and more bulky than is desirable. And the sheet support of one carriage sometimes does not support its sheet at the same level as the others.
Thus, it can be seen that it would be desirable to provide a sheet support system for use in the construction of a roof of an industrial building that precisely holds the segment of the sheet material extending from a roof insulation support carriage back to the previously installed hard roof panels so that the sheet material is properly installed without the likelihood of undesirable sagging of the sheet material between the purlins once the roof structure has been completed. It is through the provision of such that the present invention is primarily directed.